The fail criteria you want to calculate is the lack of oil in the center of the bearing?
Let's give it a try:
- See the locations of bearing and journal diameters D and d in attached file.
- Consider the journal filled with fluid of density v from the buttom to the top.
Attention: Be aware that you're actually dealing with a more dynamic problem. The journal actually empties when it's at the top due to centrifugal force (...or lack of centripetal, blah!) and has to be refilled when it reaches the bottom. If you'd like to calculate that you'd have to set up a CFD simulation because the resistance to the flow changes over time.
- Since the journal is filled fluid motion relative to the journal is neglectible.
- I calculate the amount of pressure only for the given position of the bearing. Any other position wouldn't allow fluid from inside the journal to be affected by oil pressure.
Force dF acting on a particle of fluid dV located somewhere between the centre of the bearing and the lower end of the journal, positive direction of dF is downwards:
dF = r*v*dV*w² + dV*v*g
r: Distance of dV from centre of the journal. r = 0..D
w: Rotational velocity.
g: Gravitational acceleration.
Since dF is (rather...) constant for each radius r the force acting on a disk of fluid of given distance from the centre of the journal is simply:
(Use conversion dV = dr*dA and integrate along dA)
dFa = (r*v*dr*w² + dr*v*g)*pi*d
Integrate dFa along dr from 0 to D to receive the sum of forces F acting on the cylinder of fluid:
F = pi*d*(v*w²*0.5*D² + v*g*D)
We only need the pressure and thus we receive
p = v*w²*0.5*D² + v*g*D
as a result to the pressure being necessary to keep the column of fluid from flowing back into the oil delivery system due to centrifugal forces.
Hint: That's pretty simple math and I'm sure you already wrote that down yourself. I'm just putting it up for discussion so people can comment on how valid the solution is. My personal opinion is that, even though I'm a fan of analytically solving engineering problems, this isn't one where such a solution holds much information.
Minimum oil pressure is, as far as I know, usually found by running a couple of engines on low oil pressures until they die - or hopefully survive.
Vain
Let's give it a try:
- See the locations of bearing and journal diameters D and d in attached file.
- Consider the journal filled with fluid of density v from the buttom to the top.
Attention: Be aware that you're actually dealing with a more dynamic problem. The journal actually empties when it's at the top due to centrifugal force (...or lack of centripetal, blah!) and has to be refilled when it reaches the bottom. If you'd like to calculate that you'd have to set up a CFD simulation because the resistance to the flow changes over time.
- Since the journal is filled fluid motion relative to the journal is neglectible.
- I calculate the amount of pressure only for the given position of the bearing. Any other position wouldn't allow fluid from inside the journal to be affected by oil pressure.
Force dF acting on a particle of fluid dV located somewhere between the centre of the bearing and the lower end of the journal, positive direction of dF is downwards:
dF = r*v*dV*w² + dV*v*g
r: Distance of dV from centre of the journal. r = 0..D
w: Rotational velocity.
g: Gravitational acceleration.
Since dF is (rather...) constant for each radius r the force acting on a disk of fluid of given distance from the centre of the journal is simply:
(Use conversion dV = dr*dA and integrate along dA)
dFa = (r*v*dr*w² + dr*v*g)*pi*d
Integrate dFa along dr from 0 to D to receive the sum of forces F acting on the cylinder of fluid:
F = pi*d*(v*w²*0.5*D² + v*g*D)
We only need the pressure and thus we receive
p = v*w²*0.5*D² + v*g*D
as a result to the pressure being necessary to keep the column of fluid from flowing back into the oil delivery system due to centrifugal forces.
Hint: That's pretty simple math and I'm sure you already wrote that down yourself. I'm just putting it up for discussion so people can comment on how valid the solution is. My personal opinion is that, even though I'm a fan of analytically solving engineering problems, this isn't one where such a solution holds much information.
Minimum oil pressure is, as far as I know, usually found by running a couple of engines on low oil pressures until they die - or hopefully survive.
Vain
Just out of interest, how is "items per minute" measured? Does it include the payment process or does the clock stop between the last items of customer A and the first item of customer B?
Here in Italy I'm regularly confused by the pace of the cashiers. Sure, they talk and smile a lot, but even at their best they take over a second to draw an item over their desk in a manner that it detects the item. Back in germany I usually went to a shop where they managed to deal with 2 to 3 items a second. They have really well trained personell that works like machines. Combined with electronic payment with less than 10 seconds from the last item to getting the receipt taking part in the process is really stunning from an Operations Research point of view - if you had time to think about it while hurrying to keep up with the pace of the cashier.
Vain
Here in Italy I'm regularly confused by the pace of the cashiers. Sure, they talk and smile a lot, but even at their best they take over a second to draw an item over their desk in a manner that it detects the item. Back in germany I usually went to a shop where they managed to deal with 2 to 3 items a second. They have really well trained personell that works like machines. Combined with electronic payment with less than 10 seconds from the last item to getting the receipt taking part in the process is really stunning from an Operations Research point of view - if you had time to think about it while hurrying to keep up with the pace of the cashier.
Vain
Judging by the way people dressed in the 80's I don't think so. Must've been earlier.
Though the 70's they didn't have any more sense. Neither in the 60's. 50's perhaps? Obviously not 40's. 30's not either. 20's absolutely not. ...
Has there ever been common sense?
...I wonder why they call common sense common - it appears to be anything but...
Vain
Apparently the old VW Scirocco weights about the same as a pebble. Pretty competitive in corners.
Who else thinks that Youngtimer racing in 15 years will only be a fraction as awesome as that?
*sigh*
Vain
Who else thinks that Youngtimer racing in 15 years will only be a fraction as awesome as that?
*sigh*
Vain
Am I mistaken if I believe the following method should yield the maximum senseful preload?
1. Define maximum engine torque T.
2. Multiply by smallest gear ratio r1.
3. Multiplay by differential ratio r2.
4. Multiply by differential power-locking factor F
(Assumed definition of F: F = Difference in torque between the two tyres devided by aligning input torque. Example: With F = 20% and T*r1*r2 = 20 Nm the torque split may be up to 4 Nm before slipping at the LSD clutch plates appears.)
5. If preload P is larger than T*r1*r2*F the engine will not be able to make the clutch of the LSD slip in any gear. The differential behaves as a locked diff in all power situations.
6. Define braking torque B.
7. Define braking torque split K.
[Assumed definition of K: K = (Front braking torque)/(Front braking torque + rear braking torque) as I believe it is defined in LFS ]
8. If B * (1 - K) (for RWD) respectively B * K (for FWD) are larger than preload P the brakes wouldn't be able to make the differential clutch plates slip even if one tyre was in the air and the other perfectly sticking to the ground.
I'm not quite sure how the coast locking factor works, so please feel free to comment on my ideas.
Vain
1. Define maximum engine torque T.
2. Multiply by smallest gear ratio r1.
3. Multiplay by differential ratio r2.
4. Multiply by differential power-locking factor F
(Assumed definition of F: F = Difference in torque between the two tyres devided by aligning input torque. Example: With F = 20% and T*r1*r2 = 20 Nm the torque split may be up to 4 Nm before slipping at the LSD clutch plates appears.)
5. If preload P is larger than T*r1*r2*F the engine will not be able to make the clutch of the LSD slip in any gear. The differential behaves as a locked diff in all power situations.
6. Define braking torque B.
7. Define braking torque split K.
[Assumed definition of K: K = (Front braking torque)/(Front braking torque + rear braking torque) as I believe it is defined in LFS ]
8. If B * (1 - K) (for RWD) respectively B * K (for FWD) are larger than preload P the brakes wouldn't be able to make the differential clutch plates slip even if one tyre was in the air and the other perfectly sticking to the ground.
I'm not quite sure how the coast locking factor works, so please feel free to comment on my ideas.
Vain
Going back to the topic of the 2010 F1 season, I'd like to put up a topic for discussion:
What do you folks think about the development of tyre pitstops when you can't refuel?
Since the pitlane is still as long as before but the amount of track time that can be gained by pitting more often diminishes (you can't carry less weight if you two-stop as opposed to one-stopping) I'd hazard the guess that teams will rather be contemplating no-stop versus one-stop strategies than the current one/two(/three)-stop strategies.
Alongside that point, if teams demand tyres that can take 90 minutes of racing, I'd love seeing several tyre manufacturers back in F1. It'd be pretty nice to see some cars/tyres perform better at the start, some better near mid-point and some better at the end.
Also note that from 2010 on tyre warmers will be forbidden. That means stone cold tyres for starts and pitstops (and likely teams that try to move their tyres into the sun before putting them on the car for that extra degree of heat ).
Vain
What do you folks think about the development of tyre pitstops when you can't refuel?
Since the pitlane is still as long as before but the amount of track time that can be gained by pitting more often diminishes (you can't carry less weight if you two-stop as opposed to one-stopping) I'd hazard the guess that teams will rather be contemplating no-stop versus one-stop strategies than the current one/two(/three)-stop strategies.
Alongside that point, if teams demand tyres that can take 90 minutes of racing, I'd love seeing several tyre manufacturers back in F1. It'd be pretty nice to see some cars/tyres perform better at the start, some better near mid-point and some better at the end.
Also note that from 2010 on tyre warmers will be forbidden. That means stone cold tyres for starts and pitstops (and likely teams that try to move their tyres into the sun before putting them on the car for that extra degree of heat
).Vain
You may also download the video directly here.
The Viper driver surely couldn't match the GT3 driver's extensive selection of balls. Though that really was a tough one. Especially the way he used a lapee to force the Viper into slowing down at Döttinger Höhe.
And by the way, it's really nice being able to recognize other cars on the video from either earlier onboard videos or from actually seeing them on track (I think I already posted a very good onboard video from the orange Gallardo the Viper met at Klostertal - the sound surely beats the Viper by several orders of magnitude).
When I have the time I'll skim over race-media.tv to check out the other onboard laps they host.
Vain
Judging which console is "the best" by the most objective criteria imaginable may at first look like a difficult task. However, if one takes into consideration that only one console is going to have a driving game with a Nordschleife of acceptable standard the solution should be more than obvious.
(Right now all three consoles suck equally. Once GT5 is released there'll only be one console anyone needs.)
Vain
P.S.: Back then I only got LFS as a fill-in while I waited for a proper game with the Nordschleife.
(*Sigh* I have 800€ on my account especially reserved for a PS3 + GT5 + new TV and no one except Sony wanted to claim that money in the last 3 years.)
(Right now all three consoles suck equally. Once GT5 is released there'll only be one console anyone needs.)
Vain
P.S.: Back then I only got LFS as a fill-in while I waited for a proper game with the Nordschleife.
(*Sigh* I have 800€ on my account especially reserved for a PS3 + GT5 + new TV and no one except Sony wanted to claim that money in the last 3 years.)
Doctors have told me I suffer from something similar too and that I need medication. I didn't want to consider myself the victim of some medical state and thus attacked the problem head first myself.
In simple words my strategy was and still is the following: Whenever I have a hard time concentrating on my work I just kick myself harder.
When I'm unconcentrated I have two options. I can either get back to work and actually accomplish something that I can be proud of or use some medical terms as an excuse my lack of capability.
Of course there are medical conditions which make achieving things difficult and maybe it's next to impossible to perform as well as other people, but that should merely be a motivation to try harder.
My opinion stems from the sort of obstacles people in history have overcome to achieve what they wanted. Why did they succeed while others failed? Because the others didn't kick themselves hard enough.
On the technicalities of working, beyond the motivational part, I usually chop up my work into well defined chunks. What do I want to do? What defines the finished state of my work? Which parts do I need to solve to achieve that? What qualifies each part as finished? Then I run down that list and stop for a coffee between the points.
Vain
I believe the somalians are firm pastafarians and are trying to fight global warming.
Vain
Vain
And I was talking about the fact that the UN report quoted no source/reason/proof whatsoever.
Here's a general point of criticism against the whole world: The fact that somebody else wrote it does not mean you can stop thinking for yourself.
Vain
I'm not saying it isn't true, but it is commonly known that the easiest way of making a statement appear wrong is presenting it without proof. (Q.E.D. )
Vain
)Vain
Making a statement is not making an argument.
Vain
P.S.: I found the expression "mysterious european ships" rather funny.
See attachment.I also think that the only proper way of limiting the cars is to ban refueling and giving them a certain amount of either a homologated fuel or energy in a fuel-type of the teams choosing (this involves the question of how to measure the contained energy, since not all energy in fuel is usable).
Technological advancement these days is about resource efficiency. Why is it then that efficiency plays no role whatsoever in modern racing?
(Except MotoGP I think, where I gather that they have a limited amount of fuel to drive a race with.)
Vain
P.S.: I think I just boggled my own mind with the marketing-effectiveness of limited fuel in e.g. WTCC or WRC. The statement made by superior performance in those classes could almost directly be applied to the related roadcars (at least much, much more than from F1 to roadcar). I think the manufacturers would love this.
Technological advancement these days is about resource efficiency. Why is it then that efficiency plays no role whatsoever in modern racing?
(Except MotoGP I think, where I gather that they have a limited amount of fuel to drive a race with.)
Vain
P.S.: I think I just boggled my own mind with the marketing-effectiveness of limited fuel in e.g. WTCC or WRC. The statement made by superior performance in those classes could almost directly be applied to the related roadcars (at least much, much more than from F1 to roadcar). I think the manufacturers would love this.
Last edited by Vain, .
I was thinking Western Digital "MyBook" external harddrives and their plugs.
Vain
Vain
I have to say I have a very poor impression of Quake Live.
I tried to go to the site, but it didn't support Opera, I tried in Explorer, but it doesn't support IE6. I installed IE8, I returned to the site, I downloaded the plugin and installed it, returned to the site, noticed that the mouse didn't work (in a FPS?!), went to the forum, tried a fix, didn't work, repeat, repeat, repeat, worked, played a nice skill accessment match (12:11), battled online for an hour and lost each and every game with something like 3:10 frags.
So I just spend about 2 hours on the game and had (nearly) no fun at all. Also I don't know how to uninstall the game now. It installed itself to %Application Data% which I dislike a lot since my operation system partition is meant for other things. And I can't just delete it because I don't want fragments of it floating around on my computer.
Why didn't they just offer it as a download with a msi installer? That would've saved me a lot of trouble. Bad game design.
Apart from that I disliked the mapdesign on those 4 maps I played a lot. UT had vastly better standard maps.
Vain
I tried to go to the site, but it didn't support Opera, I tried in Explorer, but it doesn't support IE6. I installed IE8, I returned to the site, I downloaded the plugin and installed it, returned to the site, noticed that the mouse didn't work (in a FPS?!), went to the forum, tried a fix, didn't work, repeat, repeat, repeat, worked, played a nice skill accessment match (12:11), battled online for an hour and lost each and every game with something like 3:10 frags.
So I just spend about 2 hours on the game and had (nearly) no fun at all. Also I don't know how to uninstall the game now. It installed itself to %Application Data% which I dislike a lot since my operation system partition is meant for other things. And I can't just delete it because I don't want fragments of it floating around on my computer.
Why didn't they just offer it as a download with a msi installer? That would've saved me a lot of trouble. Bad game design.
Apart from that I disliked the mapdesign on those 4 maps I played a lot. UT had vastly better standard maps.
Vain
Last week I watched BTCC for the first time, considered it wrecking and decided to stop watching BTCC.
I used to wonder how some people in LFS got the idea that such challanges for positions are okay, but now I see. Everywhere in the world people drive sensibly, except in the BTCC.
I really was speechless at moments where one driver intentionally wrecked a car out of the way in a manner that would get me kicked from most LFS leagues (Matt Neal comes to mind) and the commentators actually applauded the move as good racing.
Vain
I used to wonder how some people in LFS got the idea that such challanges for positions are okay, but now I see. Everywhere in the world people drive sensibly, except in the BTCC.
I really was speechless at moments where one driver intentionally wrecked a car out of the way in a manner that would get me kicked from most LFS leagues (Matt Neal comes to mind) and the commentators actually applauded the move as good racing.
Vain
As it looks they'll have most of the McLaren team in jail or executed by the end of next week.
Though I agree that blatantly lieing in front of the stewards is something that deserves a hefty penalty. It's just that excluding them from the season is even more silly than batman surfing in yellow swimming trunks.
Vain
Though I agree that blatantly lieing in front of the stewards is something that deserves a hefty penalty. It's just that excluding them from the season is even more silly than batman surfing in yellow swimming trunks.
Vain
Using hydrogen is a lot like artificially making petrol yourself from electric energy.
You take A amount of energy, use it to make B amount of fuel (very likely not at a efficiency of 100%) and use that to release C amount of mechanical energy in your vehicle (again at a efficiency lower than 100%).
Actually using hydrogen is almost completely identical to chemically producing petrol.
- Both require energy (because that's what you want to transport using your fuel, duh)
- Both require some sort of resource (be it carbohydrates in the case of petrol or water in the case of hydrogen)
- Both cause some loss of energy during production (artificial petrol much more so than hydrogen)
- Both fuels are only as safe as their containers
- Both cause some loss of energy during their conversion to mechanical energy (IC petrol engines much more so than hydrogen cell/electric motor concepts)
And by the way. You can run petrol engines on hydrogen with only small changes to the injection system (mainly the fuel pump and injection nozzle). However it's a hopeless waste of energy because even on hydrogen internal combustion engines only run at ~30-35% efficiency. A hydrogen cell in combination with electric motors is vastly superior to that (in the range of 90% efficiency).
Right now we get the energy for free by pumping the fuel out of the earth crust and releasing it into the athmosphere. Once the athmosphere is saturated we need to start making the energy terms at both ends meet.
Regarding the topic: (finally)
The design of F1 cars is solely down to the regulations. Thus if the regulations regarding wings, wheels, suspensions, driver position and air intakes don't change the design of the car won't change much either.
Vain
I guess everyone knows that at some point this concept will be very viable. However, I don't think its time has come just yet.
I'd definitely pay 20€ a month if it enabled me to play every sort of modern game without having to bother with upgrading hardware. Add to that the price of the game licenses. I think that's still a good deal for me because it'd mean that I could keep my current laptop and desktop PC for 4 years before upgrading. That's easily worth 250€/325$ per year. Add to that all the bother I save myself with reading up on hardware, reinstalling windows and driver updates, etc.
However, right now about everyone I know once in a while has issues with his internet-infrastructure. Be it random disconnects, ping spikes or WiFi issues - all these issues make gaming via stream next to impossible.
The time of gaming via cloud computing will come. But I don't think the concept will work before 5 years have passed.
Vain
I'd definitely pay 20€ a month if it enabled me to play every sort of modern game without having to bother with upgrading hardware. Add to that the price of the game licenses. I think that's still a good deal for me because it'd mean that I could keep my current laptop and desktop PC for 4 years before upgrading. That's easily worth 250€/325$ per year. Add to that all the bother I save myself with reading up on hardware, reinstalling windows and driver updates, etc.
However, right now about everyone I know once in a while has issues with his internet-infrastructure. Be it random disconnects, ping spikes or WiFi issues - all these issues make gaming via stream next to impossible.
The time of gaming via cloud computing will come. But I don't think the concept will work before 5 years have passed.
Vain
Slight correction, he didn't get any magic pace out of the car. Qualified 15th without actually attempting Q2 and got 13th fastest laptime in the race. Sounds to me like he just did his thing and floated to the top as the others failed. The tyre strategy and KERS likely helped a lot with not getting stuck behind anyone. He seemed more silently consistent than shining.
I'm not saying Lewis' drive wasn't great, just not exceptional. Almost everyone performed very well and it's difficult to find anyone who outperformed everyone. There was no lone shining star like e.g. last year at Monza.
I'd perhaps pick Buemi. He really jumped his own shadow I think - I never had him on my map as a driver that can mix it up with great drivers like Hamilton or Massa. I originally had him down as a Piquet sort of driver that crashes when somebody tells him a WDC is driving behind him. Buemi didn't set the world on fire, but drove vastly better than I would've predicted.
Vain
Last edited by Vain, .
Reason : Forgot that that was 10 seconds after the end of SC phase.
I thought the new regulations were rather useless in the beginning, however it has put quite a lot of teams off the rails while some smaller teams ended up in the front. I believe that the other teams that dropped behind compared to last season will catch up quickly and thus we will see a shift in balance over the course of the year, which could very well lead to an incredible championship.
E.g. Button will likely be gone and away at Australia and comfortably lead the race, but I don't think BrawnGP can maintain such a dominating position for the whole season. Thus we'll likely see several teams at the top at some point of time during the season. If we're lucky the first WDC with the race-wins system might be wide open until the last few races because no one managed to get more than 3 racewins.
Though I personally wish a swift and painfull demise to the new WDC system and the guy who thought of it.
Vain
E.g. Button will likely be gone and away at Australia and comfortably lead the race, but I don't think BrawnGP can maintain such a dominating position for the whole season. Thus we'll likely see several teams at the top at some point of time during the season. If we're lucky the first WDC with the race-wins system might be wide open until the last few races because no one managed to get more than 3 racewins.
Though I personally wish a swift and painfull demise to the new WDC system and the guy who thought of it.
Vain
They didn't give a status report, they published a likely release date. Apparently that wasn't smart.
Vain
Vain
Is it normal that british commentators loud and clearly burp into the microphone without at least excusing themselves?
(At least something worth staying up for...)
Vain
(At least something worth staying up for...)
Vain
FGED GREDG RDFGDR GSFDG